This invention relates generally to the monitoring of internal deterioration of machinery such as compressors, motors, engines, turbines, gear drives, etc., by detection of contaminants, including moisture and magnetic particles in fluids such as lubricating oil and refrigerant.
Internal deterioration of machinery has heretofore been monitored by physical examination of the filter media associated oil filters utilized to reduce wear of the machinery by recirculated wear particles. Magnetic probes involving the use of a permanent magnetic tip exposed to the fluid of the lubricating system of the machinery have also been utilized for some time to attract and hold magnetic particles. The magnetic particles so accumulated have been physically examined to determine the degree of wear involved.
Another known method of determining internal deterioration of machinery involves the spectral chemical analyses of the lubricating fluids. Such systems for monitoring the internal condition of machinery do not provide any determination as to the amount of free carbon in the lubricating oil and do not provide any indication of excess heat in the system.
Yet another known method of monitoring internal deterioration of machinery involves the microscopic examination of wear particles in samples of the lubricating fluid. None of the foregoing methods for monitoring machinery deterioration by examination of the circulating fluids provides an early warning of damage and shut down of the machinery before damage occurs.
Contamination of circulating fluids such as refrigerant and lubricating oil with moisture and associated contaminants such as acids resulting from chemical breakdown have heretofore been detected by means of sensor probes such as that disclosed in my prior U.S. Pat. No. 3,846,730, issued Nov. 5, 1974. According to such patent, the sensor probe exposed an absorbent material to the fluid causing a change in electrical resistance or conductivity thereof as a function of fluid contamination. The absorbent material is clamped between electrode discs and retained in place by an annular fabric element. One of the electrode discs is grounded while the other disc provides a resistance signal reflecting the level of contamination. According to my related U.S. Pat. No. 3,959,980, issued June 1, 1976, such resistance signal is fed to a two-stage detection system through which audio and visual alarm signals are generated and shutdown effected before equipment damage occurs.
It is therefore an important object of the present invention to provide an improved sensor probe and detection system for lubricating oil from which an analog signal is generated, the system being reversible to enable continuous monitoring with respect to a wide range of contaminants.
An additional object of the invention in accordance with the foregoing object is to provide early warning signals and/or shut down machinery prior to irreparable damage thereto in response to the aforementioned detection of fluid contamination.